Background:

This guideline provides an overview of how to design and implement a REST API interface for querying patient demographic data from an Electronic Patient Record (EPR) system using HealthConnect. The process involves sending a query request with the patient's identification number, retrieving the response from the EPR system, extracting the required patient demographic data from the HL7 message, and sending it as a JSON response to the supplier. The high-level process diagram is shown below (Screenshot 1).

Note: You can modify or add code and other features according to your requirements. This is just a basic guideline I’ve created for quick solutions.

Screenshot 1: A High-Level Message Process Diagram.

The step-by-step guideline is provided below:

1. Setup HealthConnect Management Portal (MP) – Production Configuration (PC).
2. Custom Code
3. Using Postman

Step 1: Set Up Web Application
 

Set up the REST service in the HealthConnect Management Portal.

1. Go to System Administration → Security → Application → Web Application.
2. Click "Create New Web Application".
3. Enter the name of the application.
4. Provide a description (optional).
5. For Namespace, select the appropriate namespace.
6. Click on REST (for enable).
7. Enter the Dispatch Class.
8. Select "Unauthenticated" (I will later explain how to set up a password)
9. And click "Save". See the screenshot 2 below (example):

Screenshot 2: Web Application and Setting Up REST

Step 2: Create Required Classes

A. Create Class - GetRequestDatasets

• Open Cache Studio and select the appropriate namespace (where you set it up).
• Create a new class by clicking File → New → General → Class Definition → OK.
• Enter the package name and class name "GetRequestDatasets". See Screenshot 3 below:

Screenshot 3: Code for GetRequestDatasets

B. Create Response Datasets Class

Note: You can add or remove properties according to your requirements.

• Class name "SetResponseDatasets", then write the following code and compile it. (See Screenshot 4 below.)

Screenshot 4: Code for SetResponseDatasets

C. Create Business Process  

• Name the Business Process "QueryRequestResponse", then write the following code and compile it. (See Screenshot 5 below.)

Screenshot 5: Code for Business Process - QueryRequestResponse  

Continue..

Note: "404 Not Found" is just a display message, but you can set this up differently.

D. Create Business Servies  

• Name the Business Service "GetRequest", then write the following code and compile it. (See Screenshot 6 below.)

Screenshot 6: Code for Business Process - QueryRequestResponse  

E. Create Rest Handler  

• Name the Rest Handler "RestHandler", then write the following code and compile it. (See Screenshot 7 below.)

Screenshot 7: Code for RestHandler  

In the Studio, your final layout should look like the screenshot (8) below:

Screenshot 8: Studio Layout of Restful API

Step 3: Set Up Management Portal : Production Configuration.

Give the names (services, processes, operations) according to your requirements.

• Services: Select the appropriate class → ...RESTfulAPI.SERVICES.GetRequest
• Processes: Select the appropriate class → ...RESTfulAPI.PROCESS.QueryRequestResponse
• Operations: Select EnsLib.HL7.Operation.TCPOperation (for EPR System)

Note: Go to Service’s settings and select the process name from the dropdown list that you have defined. See Screenshot 9 below

Screenshot 9: The management portal: production configuration view.

Finally, we have set up everything. Now, let's test or evaluate the interface.

Step 4: Testing and Evaluation

I am using POSTMAN, so download and install POSTMAN if you don’t have it already.

Test Case 1: Request with a valid Patient MRN Number using POSTMAN (GET à https://......restapi/Patient?MRN=510800

Screenshot 10: Output of Test Case 1.

Test Case 2: Request with a valid Patient MRN Number using POSTMAN (using different way) https://......restapi/510800

Screenshot 11: Output of Test Case 2.

Test Case 3: Request with an invalid Patient MRN Number using POSTMAN

Screenshot 12: Output of Test Case 3.

Test Case 4: If the Management Portal's services are disabled, the following message will appear.

Screenshot 13 (a): Disabled Services - Output of Test Case 4.

Screenshot 13 (b): Disabled Services - Output of Test Case 4.

Let’s look at the message visual trace

Screenshot 14 : Visual Trace

Screenshot 15 : Source Message:

Screenshot 16: Process Message - Generate Message – QRY Q01 message sent to the operation

Screenshot 17: Response from the EPR System – ADR^A19 (Operation)

Screenshot 18: Process Message - Extract the required data from the A19 message.

I hope this will help you. Regarding the use of the database for QueryResponse and other features of the RESTful API, I will provide an update later.